Methods and devices for charging a battery are believed to be discussed in the related art. By the term battery one should also understand, in this instance, individual or several cells of a battery or of an accumulator. For lithium ion batteries it is particularly known that one may use the so-called IU charging method, which is also designated as CCCV charging method (constant current constant voltage). In this method, the battery is charged in a first phase (I charging) at constant current, while the charging voltage increases. The current is limited, in this instance, by a current regulator of the device, or rather, of the charging unit. Upon reaching a selected end-of-charge voltage at the battery, one switches over from constant current control to voltage control, at which the battery is loaded further at constant voltage. At an increasing charging level of the battery, the charging current drops automatically. It is known that, as a criterion for ending the charging, one may use the falling below of a specifiable boundary value by a falling charging current.
In order to carry out or map the abovementioned charging method, the recording of the charging current and its preparation in signal technology are required.